An in-vehicle system (IVS) captures data such as location data and in an emergency automatically places a call to an emergency call taker or Public Safety Answering Point (PSAP) via a wireless telecommunications network. After a voice call session is established, the IVS transmits a predetermined control signal through the voice channel. The control signal directs the call taker system to prepare to receive data. Preferably, the control signal comprises at least one audio frequency tone. This may be done without human intervention. After transmission of essential information, the IVS system may switch on audio connections for live human voice conversation.
An apparatus for providing useful data in association with a high-priority call such as an emergency includes data (e.g., an MSD or FSD) embedded within one or more real-time protocol packets such as RTP Control Protocol (RTCP) packets, that are interspersed within the voice or user data stream (carried in e.g., RTP packets) of an emergency call. The apparatus transmits the data portion reliably from the initiating terminal (e.g., an in-vehicle system) to a PSAP, by using the same transport connection as the user data.
A system and method to be used with first and second devices capable of communicating using a subset of different modulation schemes include optimizing transmission of data from the first device to the second device when receiving a trigger signal from the second device. The transmitted trigger signal includes data transmitted using a sequence of at least two of the modulation schemes. The system and method analyze the received trigger signal to identify one of the modulation schemes as a function of the received trigger signal as an initial modulation scheme to be used to transmit data to the second device and transmit the data from the first device to the second device. See, for example, U.S. Pat. App. 2010/0227584; U.S. Pat. App. 2010/0202368; and U.S. Pat. App. 2010/0069018.